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            <div class="demo01"></div>
            <div class="demo02"></div>
            <div class="demo03"></div>
            <style>
                div {
                    border: 5px solid #333;
                    width: 200px;
                    height: 200px;
                    margin-bottom: 20px;
                }
            
                .demo01 {
                    background-color: rgb(108, 55, 82);
                }
            
                .demo02 {
                    background-color: rgba(39, 97, 148, .3);
                    transition: background-color 1s;
                }
            
                .demo03 {
                    background-color: #571717;
                }
            </style>
                     <hr>
                     源代码
                     <pre>
                                &ltdiv class="demo01">&lt/div>
                                    &ltdiv class="demo02">&lt/div>
                                    &ltdiv class="demo03">&lt/div>
                                    &ltstyle>
                                        div {
                                            border: 5px solid #333;
                                            width: 200px;
                                            height: 200px;
                                            margin-bottom: 20px;
                                        }
                                    
                                        .demo01 {
                                            background-color: rgb(108, 55, 82);
                                        }
                                    
                                        .demo02 {
                                            background-color: rgba(39, 97, 148, .3);
                                            transition: background-color 1s;
                                        }
                                    
                                        .demo03 {
                                            background-color: #571717;
                                        }
                                    &lt/style>
                     </pre>
 

      
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